1. Field of the Invention
The present invention relates to an electronic apparatus having a main case covering a plurality of operators so as to allow these operators to be operated, a first board having formed thereon electric circuitry for processing signals generated by operations of the operators, and a second board having formed thereon electric circuitry for further processing signals generated at least by the first board.
2. Description of the Related Art
In conventional electronic apparatuses having a large number of operators in particular, it is desirable to dispose these operators on a large operating panel surface (housing surface). Therefore, in some electronic apparatuses of this type, a first board (operating circuit board) on which is formed electric circuitry for performing processing related to operators such as switches and a display is disposed under the operating panel surface, and further a second board (circuit board) on which is formed electric circuitry for performing further processing signals from the electric circuitry of the first board is disposed under the first board.
In the prior art, to assemble the first and second boards to a main case, the second board is mounted in a lower case, and the first board is mounted in an upper case (operating panel) such that it is attached to bosses suspended from the upper case using screws or the like. The bosses are welded to the upper case when the upper case is made of metal, or the bosses are formed integrally with the operating panel when the upper case is made of resin.
However, when the operating panel is made of metal, welding marks are noticeable even if the surface of the operating panel (operating panel surface) which is opposite the boss welded portions is coated with a paint. Therefore, the operating panel is often coated in a dark color (black) so as to make the marks as unnoticeable as possible. The color of the operating panel surface is thus limited and often monotonous. Further, when the operating panel is made of resin, shrinkage concavities (concave portions created by shrinkage of the resin during molding solidification) may be formed in the operating panel surface. The bosses are thus made as thin as possible. Alternatively, to reduce the volume of the bosses, the bosses which are formed integrally with the operating panel are comprised of two thin ribs to which the board is attached using screws. Consequently, in the former case, the bosses are not durable enough, whereas in the latter case, costs increase. Further, there are problems that, if the shrinkage concavities in the operating panel surface are neglected, the apparatus does not appear to have high quality and can be mistaken as a defective. Further, the operating panel surface constitutes a display section showing characters and the like. Accordingly, if the shrinkage concavities in the operating panel surface are neglected, the operating panel surface may not only lack readability but may also fail to be properly printed because of the shrinkage concavities.
Further, in the conventional electronic apparatuses having a large number of operators in particular, it is desirable to dispose these operators on a large operating panel surface (housing surface). Therefore, in some electronic apparatuses of this type, an operating circuit board on which operating elements such as switch devices are mounted is disposed under the operating panel surface. Further, the operating elements such as the switch devices mounted on the operating circuit board are operated using operators such as knobs, buttons, or dials.
However, it takes considerable time and labor to connect (attach) these operators to the operating elements (devices). Further, if the height of the operating elements such as the switches varies between a plurality of electronic apparatuses of the same type even with the same two-dimensional arrangement of the operating elements such as the switches with respect to the operating panel surface or if the height of the operating circuit board (the distance to the operating panel surface) varies between a plurality of electronic apparatuses of different types, then the use of common members such as a main case is effective for reducing costs.